(a) Field of the Invention
The present invention relates to a method of establishing anchor stanchions on concrete bridge beams that can be anchored to the standard loop type rebar that protrudes from the top of concrete bridge beams.
Additionally this invention relates to a method to tie back the anchorage stanchions to increase their load carrying capability.
(b) Discussion of Known Art
Horizontal Lifeline systems are currently used for fall protection on many applications involving bridge building and other construction activities. Bridge beams currently have looped rebar protruding from the top of the prestressed beams that are used to provide attachment points for the decking that is laid over them. Workers that work atop these beams need fall protection while laying the decking. Currently horizontal lifelines are attached to this rebar, but the lifelines lay on top of the concrete beams. When attached to these lifelines a worker, using a six-foot shock absorbing lanyard will fall 12 feet before his lanyard begins to pull on the lifeline. The U.S. Occupational Safety and Health Administration (OSHA) requirements state that all fall protection systems must be rigged so that a worker may not experience more than six feet of free fall. For this reason there existed a need to develop a stanchion system that will raise the horizontal lifeline five feet above the walking/working surface. This five foot elevation is the same elevation as the Dorsal D-ring on the worker""s harness. When using a six foot shock absorbing lanyard and a stanchion assembly that will support a horizontal lifeline (HLL) at least five feet above the walking/working surface the six foot freefall limitation required by OSHA will be met.
This present invention relates to a method of installing horizontal lifeline systems on looped rebar bridge beams with stanchions that will support the lifelines at least five feet above the top, (walking surface) of the bridge beam.
An example of a lifeline support that includes a stanchion can be found in U.S. Pat. No. 5,863,020, to Olson et al., incorporated herein by reference.
It has been discovered that the problems left unanswered by known art can be solved by The present invention relates to an improved method of installing horizontal lifelines on stanchions to concrete bridge beams that contain looped rebar protrusions along their top. This invention provides for a method to install the stanchions and a method to cause the stanchions to lean left, right or stand centered to provide ease of access for the workers. This invention also provides a method to tie back the stanchions for additional support. It allows for lifelines that can support at least 7,500 lb. Of line tension with a 2 to 1 safety factor and can be used by up to 4 persons at one time. It provides end stanchions for anchorage of the horizontal lifelines and bypass stanchions which are used to shorten apparent span lengths to decrease free fall distances and horizontal lifeline sag height.
Thus, when using the disclosed system and method, the user will also carry out the following steps:
a. Providing an anchorage stanchion receiver that will attach to looped rebar.
b. Providing a HLL end stanchion that will attach to the stanchion receiver.
c. Providing a HLL bypass stanchion that will attach to the stanchion receiver.
d. Providing a tie back cable assembly that will attach the end stanchions to the looped rebar.
e. Providing a horizontal lifeline system that will attach to the end stanchions.
In another aspect this invention relates to a method to adjust the stanchion system from one side of the concrete bridge beam to the other side. This feature allows the worker to work on either side of the bridge beam and also allows the stanchion to be shifted out of the way when decking is being lowered into place over the bridge beams with a crane.
It should also be understood that while the above and other advantages and results of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings, showing the contemplated novel construction, combinations and elements as herein described, and more particularly defined by the appended claims, it should be clearly understood that changes in the precise embodiments of the herein disclosed invention are meant to be included within the scope of the claims, except insofar as they may be precluded by the prior art.